Mac: Here's a great way to quickly forward a link to a web page you're reading: hit command, shift, and "i" and an email message will automatically open with the page title in the subject and the link in the body.

The shortcut works with Chrome and Safari on the Mac, and tests out for both Mail and Thunderbird. I tried it on Windows 7, but no dice, unfortunately, and the shortcut didn't work with Firefox on either Windows or Mac; if you have better luck, though, let us know in the comments.